Generally, heart rate is defined to be the times of heartbeats in one minutes of a person, which is an important medical index reflecting the health condition of the person, and also one important basis for patient care, for directing one to form a good daily routine, and for directing the athletes to train scientifically. The most common apparatus for heart rate detection is stethoscope including many kinds, such as, single head stethoscope, double head stethoscope, triple change stethoscope, stand-type stethoscope, universal stethoscope, and recently appeared electronic stethoscope and the like. In spite of the low price and convenience in use, it's difficult for ordinary persons without professional training to obtain the accurate value of the heart rate using the stethoscope. For example, improper wearing of the stethoscope leads to loose contact between the earplug and the ear canal, such that sounds might leak out, causing a bad auscultation effect; moreover, noise outside might enter to confuse the auscultation effect, such that the value of the heart rate cannot be detected accurately. For another example, if the stethoscope is put in the pocket all the time or not maintained periodically, cotton fiber of the cloth, fiber or dust might block the tube of the stethoscope, which would affect the accuracy of auscultation. Moreover, the accuracy of the stethoscope is so limited that slightly heartbeats or pulse in the irregular heartbeats might be omitted, which also reduces the accuracy.
Recently, with development of photoelectric technology, Photoplethysmograpy (PPG) is widely used in heart rate detection. FIG. 1 is a schematic view of the use of heart rate detection apparatus in the prior art. As shown in FIG. 1, the heart rate detection apparatus 1 is worn on the ear 2, and includes a data processing device, a light source disposed behind the ear, and a sensor located in the auricle and opposite to the light source. After the light signal from the light source transmits through the cartilage of the auricle and is received by the sensor, the date processing device processes the light signal detected by the sensor so as to obtain the heart rate information by computing. The above-mentioned heart rate detection apparatus measures the heart rate by using the light transmission PPG, and the user can wear this heart rate detection apparatus for long time. However, as shapes of auricles of people differ from one another, and the relative position between the heart rate detection apparatus and the auricle cannot keep stable when people move, there occur the conditions that the light signal emitted from the light source cannot transmit through the blood vessel in the auricle or other pulsing region, resulting in weak light signals detected by the sensor, such that the heart rate detection apparatus cannot obtain the heart rate information accurately and reliably.